diff --git a/proxy/src/main/java/com/glyart/authmevelocity/proxy/AuthMeVelocityPlugin.java b/proxy/src/main/java/com/glyart/authmevelocity/proxy/AuthMeVelocityPlugin.java
index 8c8b80b..157c135 100644
--- a/proxy/src/main/java/com/glyart/authmevelocity/proxy/AuthMeVelocityPlugin.java
+++ b/proxy/src/main/java/com/glyart/authmevelocity/proxy/AuthMeVelocityPlugin.java
@@ -4,6 +4,7 @@ import com.glyart.authmevelocity.proxy.config.AuthMeConfig;
 import com.glyart.authmevelocity.proxy.listener.FastLoginListener;
 import com.glyart.authmevelocity.proxy.listener.PluginMessageListener;
 import com.glyart.authmevelocity.proxy.listener.ProxyListener;
+import com.google.common.collect.Sets;
 import com.google.inject.Inject;
 import com.velocitypowered.api.event.Subscribe;
 import com.velocitypowered.api.event.proxy.ProxyInitializeEvent;
@@ -15,8 +16,6 @@ import org.jetbrains.annotations.NotNull;
 import org.slf4j.Logger;
 
 import java.nio.file.Path;
-import java.util.Collections;
-import java.util.HashSet;
 import java.util.Set;
 import java.util.UUID;
 
@@ -26,7 +25,7 @@ public class AuthMeVelocityPlugin {
     private final Path pluginDirectory;
     private static AuthMeVelocityPlugin plugin;
 
-    protected static final Set<UUID> loggedPlayers = Collections.synchronizedSet(new HashSet<UUID>());
+    protected static final Set<UUID> loggedPlayers = Sets.newConcurrentHashSet();
 
     @Inject
     public AuthMeVelocityPlugin(ProxyServer proxy, Logger logger, @DataDirectory Path dataDirectory) {
@@ -45,8 +44,10 @@ public class AuthMeVelocityPlugin {
             MinecraftChannelIdentifier.create("authmevelocity", "main"));
         proxy.getEventManager().register(this, new ProxyListener(config));
         proxy.getEventManager().register(this, new PluginMessageListener(proxy, logger, config));
-        proxy.getPluginManager().getPlugin("fastlogin").ifPresent(fastlogin ->
-            proxy.getEventManager().register(this, new FastLoginListener(proxy)));
+
+        if(proxy.getPluginManager().isLoaded("fastlogin")){
+            proxy.getEventManager().register(this, new FastLoginListener(proxy));
+        }
 
         logger.info("-- AuthMeVelocity enabled --");
         logger.info("AuthServers: {}", config.getAuthServers());
diff --git a/proxy/src/main/java/com/glyart/authmevelocity/proxy/config/ConfigUtils.java b/proxy/src/main/java/com/glyart/authmevelocity/proxy/config/ConfigUtils.java
index a27e993..18c02d6 100644
--- a/proxy/src/main/java/com/glyart/authmevelocity/proxy/config/ConfigUtils.java
+++ b/proxy/src/main/java/com/glyart/authmevelocity/proxy/config/ConfigUtils.java
@@ -14,4 +14,5 @@ public class ConfigUtils {
                     blockedMessage));
         }
     }
+    private ConfigUtils(){}
 }